1. Field of the Invention
This invention relates to disk drive systems, and relates more particularly to such disk drive systems having a low height or profile, improved serviceability, reliability and removability without sacrificing capacity or performance.
2. Prior Art
Over the past ten years, disk drive devices for use in computer systems have been dramatically shrinking in size. One of the factors responsible for this rapid progress has been the ability to reduce the space required to house the electronic components of the devices, made possible principally through very large scale integration of the electronic circuitry. Additionally, substantial advances have been made in reducing the size of the major mechanical components of disk drive devices such as the motor which rotates the disk or disks, the flexure mounting mechanism for the read/write heads and the actuator mechanism which moves the heads to different track positions on the disk surfaces.
With the increasing popularity of portable, laptop, notebook and smaller desktop personal computers employing disk drives, the pressure to reduce the volume of the disk drive enclosure without sacrificing the capacity, performance and cost of the storage device is significant. A hard disk drive manufacturer must supply a product having a very high linear bit density and radial track density in a device that is resistant to shock and vibration, is temperature and environment tolerant, is producible in high volume at a reasonable cost, has high throughput performance, and has a storage capacity that meets the increasing data storage requirements of the computer system market. In most small computer systems, the size of the keyboard and the visual display or monitor will dictate the mandatory X and Y dimensions for the system. This means that the most critical disk drive dimension that can be controlled is the height or Z dimension of the drive.
The relatively recent introduction of 2.5 inch and 1.8 inch "form factor" disk drives has been a response to this demand for high capacity, low volume storage for the smaller types of computers. Representative examples of prior art disk drive designs directed to the 2.5 inch and 1.8 inch form factor drives are the following.
U.S. Pat. No. 5,025,335, Stefansky, shows a disk drive employing a 2.5 inch disk in a housing whose length is described as equal to the width of a conventional 3.5 inch disk drive (4 inches) and whose width is approximately one half the length of a 3.5 inch drive (2.75 inches). In an embodiment with one disk in the housing, the height of the unit is 0.68 inches, with a printed circuit board containing the drive electronics mounted adjacent to and outside the bottom of the housing.
U.S. Pat. No. 5,025,336, Morehouse et al, discloses a reduced height disk drive with a single 2.5 inch disk therein, the drive housing having a width of approximately 2.8 inches, a length of approximately 4.0 inches and an overall height no greater than 0.63 inches. The patent attributes this reduced height to the use in the disk enclosure of disk spin motors, actuators and head flexures of smaller height. This drive utilizes a printed circuit board with the drive electronics therein disposed below the base which supports the disk and actuator and outside the disk enclosure.
U.S. Pat. No. 4,933,785, Morehouse et al, shows a drive containing at least two 2.5 inch disks therein, with the printed circuit board containing the device electronics mounted below and spaced from the disk enclosure.
U.S. Pat. No. 5,038,239, Vettel et al., discloses a disk drive in which the electronic circuits are disposed mounted on a number of circuit cards which are mounted in different areas in the drive housing, with interconnections between the multiplicity of cards.